The invention relates to novel x-ray contrast agents, the preparation thereof and to roentgenographic contrast media based thereon.
3-Acylamino-5-alkylcarbamoyl-2,4,6-triiodobenzoic acids are known from U.S. Pat. No. 3,145,197. Several amino acid derivatives of 3-acylamino-5-alkylcarbamoyl-2,4,6-triiodobenzoic acids have likewise been described, e.g., 5-acetamido-2,4,6-triiodoisophthaloyl diglycine in U.S. Pat. No. 3,102,880 and N-[3-N-(alkyl-acylamino)-5-alkylcarbamoyl-2,4,6-triiodobenzoyl]-amino acids in Helv. Chim. Acta 54 (8): 2551-2559 (1971). Although these compounds have a low toxicity, they have several undesirable side effects. For example, they do not meet the high requirements to be fulfilled by a medium for myelography, e.g., see Ugeskrift for laeger 134 (18): 936 (1972) and Advances in X-Ray Technology 115: 683-684 (1971).
Other teachings on highly iodinated aromatic compounds are those of Erich Klieger et al., U.S. Pat. No. 3,953,501; Heinz Gries et al., U.S. Pat. No. 4,001,298; Heinz Gries, U.S. Pat. No. 3,883,578; and Erich Klieger et al., Ser. No. 555,043, filed Mar. 3, 1975, now allowed, the disclosures of which are herein incorporated by reference.